By SCOTT GUTIERREZ, SEATTLEPI.COM STAFF

Published 10:00 pm, Thursday, February 18, 2010

King County officials plan to conduct another study of the South Park Bridge to re-assess its stability and how much longer the deteriorating drawbridge can stay open while they look for money to build a replacement.

The drawbridge, which carries 20,000 vehicles per day across the Duwamish Waterway and serves as a major freight connection in South Seattle city limits, is scheduled to be closed in June. On Wednesday, county officials learned their application for a $99 million federal grant to help pay for a new bridge was turned down in favor of two other Washington state projects, including Seattle's Mercer Corridor reconfiguration through South Lake Union.

With no immediate solutions in hand for the $150 million price tag, county officials see few incentives to continue thowing money at stopgap repairs on the current span. County officials also are running out of things they can do to keep the bridge working. Maintenance and operation costs are about $300,000 each year, with about 30 percent of that to keep it functional.

Still, no one is thrilled about closing the 78-year-old span, which links arterial East Marginal Way South with State Route 99 and serves as one of two main connections for residents in the Duwamish Industrial area. For residents in isolated South Park, it is a prime link to other neighborhoods across the river. Closing it would cut off the low-income neighborhood and likely congest the First Avenue South bridge, the nearest crossing downriver.

"We just want to double check that we are correct in our current understanding of the bridge's condition and it's worthiness to continue to be in service through June," said Linda Dougherty, director of the King County Road Services Division. "We also want to make sure there is not something we overlooked. The bridge may reasonably have more life in it beyond the end of June."

Even if does stay open longer, it likely would be a matter of months, she said.

A disappointed King County Executive Dow Constantine proclaimed his administration would continue working on a financing plan, possibly applying for a second round of TIGER funding, or getting help from a federal jobs bill that still sits before Congress.

"While the bridge competed against a lot of other worthy projects, replacing this key transportation link is imperative to the economic health of affordable, diverse neighborhoods and the hundreds of industrial businesses that depend on direct vehicular access to State Route 99 and Interstate 5," Constantine said in a statement. "It may not be a glamorous or high-profile project, but it's one that is vitally important to our economy and our society."

Constantine said Thursday on KUOW that when the bridge is closed, it will have to be demolished under federal law because it sits in a navigable waterway.

After a news conference about the Mercer project, Sen. Patty Murray, D-Wash., said there would be another pot of money coming, but that she would urge the county to collaborate with city and state partners in putting a financing plan together to boost the project's competitiveness.

The bridge is falling apart largely due to the way it was built in 1929. The engineers didn't drive the piles of the north pier deep enough into the riverbed, so piers on both ends are drifting apart and tilting inward, causing misalignment in the leaves. Engineers have had to repeatedly shorten interlocking metal teeth at the end of each span so the bridge will close properly. Now, the teeth are down to nubs.

The bridge was damaged during the 2001 Nisqually earthquake and the foundation is cracking. In a recent inspection, it scored a 4 in a sufficiency scale of zero to 100 -- the lowest rating of any bridge in the state.

Current data on the bridge comes from a study completed in 2005. The bridge recently was fitted with numerous electronic motion sensors. In addition, the bridge's piers have been equipped with "tiltmeters" to measure movement. The newest study would analyze data from both.

One thing county engineers are assessing is how sturdy the bridge is for oversized freight loads, Dougherty said.

"When large trucks go over, we know from the data that in areas where concrete is cracked -- the cracks open more when a fully loaded truck passes overhead," Dougherty said.

While the bridge serves Seattle and Tukwila, it touches down in an orphaned slice of unincorporated land between both cities' boundaries, making it King County's responsibility.

In January, the County Council approved a Transportation Benefits District under which they could impose a licensing fee to raise up to $30 million in matching funds. So far, no new tax has been authorized.

An environmental-impact study was completed last year for the new bridge, meaning the project is shovel ready. County officials say the new bridge could be completed in two years. Recent testing was done to determine whether driving piles for a new bridge would affect the existing one.

There was no estimate yet on how much the study would cost, but Dougherty said it likely would be below $500,000, which is the threshhold at which the roads division would put a contract out to bid. Under that limit, the study could be handled by on-call consultants, she said.